Field of the Invention
The present invention relates to a magnet chuck that attracts and retains a workpiece by the magnetic force of a permanent magnet.
Description of the Related Art
A magnet chuck includes either one of an electromagnet or a permanent magnet. In the case of an electromagnet, a magnetic force is generated by starting supply of current (i.e., energizing) to the electromagnet, and the workpiece is attracted and retained by the magnetic force. Further, when supply of current is stopped, the magnetic force disappears, and as a result, the workpiece is released.
On the other hand, in the case of a permanent magnet, for example, as disclosed in Japanese Laid-Open Patent Publication No. 55-078505, an arrangement exists for attraction and retention as well as releasing of the workpiece to be switched by rotating the permanent magnet. However, more generally, an arrangement is known in which the permanent magnet is connected to a piston, and the permanent magnet is displaced together with the piston (for example, see Japanese Laid-Open Utility Model Publication No. 51-102174). With the magnet chuck disclosed in Japanese Laid-Open Utility Model Publication No. 51-102174, following along with the displacement of a piston that has received a pressure fluid, a permanent magnet is brought into close proximity to a workpiece, then the workpiece being attracted and retained thereby. Further, when the permanent magnet and the piston are displaced in a direction to separate away from the workpiece, the workpiece is released.
This type of magnetic chuck, for example, is disposed on a distal end arm of a robot, and accompanying the robot performing a predetermined operation, the attracted and retained workpiece is transported to a predetermined position.